
\begin{tikzpicture}[scale=.8]
  \tkzDefPoints{0/0/O,-2/0/A,5/3/C,5/0/H,2/0/D}
  \tkzInterLC(A,C)(O,A) \tkzGetFirstPoint{B}
  \tkzDrawPolygon(A,C,H)
  \tkzDrawSegment[dashed](B,D)
  \tkzDrawCircle(O,A)
  \tkzMarkRightAngle(C,H,A)
  \tkzMarkRightAngle(A,B,D)
  \tkzDrawPoints(O,A,B,C,D,H)
  \tkzLabelPoints[above](B,C)
  \tkzLabelPoints[below](O,H)
  \tkzLabelPoints[below right](D)
  \tkzLabelPoints[left](A)
\end{tikzpicture}
